I know Solidworks Simulation automatically uses K factors based on things like Rourke's formulas, but is there any way to display what the K factor currently is? Especially for a pressure vessel study.

Kt=1 in all cases. It has no provisions to account for notch sensitivities other than through modeling the geometry and implicit in that is you have a mesh independent solution in the area of interest.

As Bill said, that's not the way FEA works. If you put a sharp corner in a bar that you are bending, you will get a high stress at the sharp corner. As you refine the mesh to finer and finer elements, the stress will continue to rise. In theory, as the size of the mesh goes to 0 the stress goes to infinity. In practice, it just keeps getting larger and larger as the mesh gets smaller.

If you put a radius on that corner, the stress will approach the value you would get from Roark and Young as you refine the mesh. That is not because they use formulas from Roark and Young, it is because the solution accuracy gets closer and closer to 100% as the mesh gets smaller. The reported stress is getting closer and closer to the actual stress.